In recent years it has become increasingly desirable to improve the combustion of the compressed gas mixture in an internal combustion engine to reduce the levels of pollutants released to the atmosphere and provide improved efficiency of the engine for higher gas mileage.
One method of improving the efficiency is to supply additional air to the compressed gas mixture during the period of flame propagation in the combustion cylinder. This may be accomplished by introducing air, under substantially constant pressure, to a combustion cylinder at a time when the pressure within the combustion cylinder is less than the pressure of the constant pressure air and interrupting the supply of constant pressure air when the pressure within the combustion cylinder exceeds the constant pressure.
To achieve such interruptable air supply, elaborate methods and apparatus have been devised that comprise one or more check valves that operate to open and close passage from the constant pressure air supply source, in response to differentials between the constant pressure of the air supply and the pressure changes within the combustion cylinder. Such systems have included air supply inlets at various locations within the combustion cylinder and have included elaborate spark plugs configured with passageways to provide an inlet to the combustion cylinder.
Spark plugs have been proposed that contain various passageways for air transmission through the spark plug to the combustion cylinder. Some have even proposed using a hollow central electrode for a passageway but none appear to have enjoyed widespread commercial success. The problem has been that regardless of the type of system heretofore proposed for a spark plug passageway, the back-pressure on the air inlet mechanism produced by the combustion process is so great that there is a tendency for the system to break down and/or become fouled with carbon deposits thus significantly reducing the useful life of the spark plug.
It is an object of this invention to provide an improved spark plug for injecting air into the combustion cylinder of an internal combustion engine.
It is another object of this invention to provide a spark plug for an air-injection system that reduces compression back pressure to the system.
It is a further object of this invention to provide an air-injection spark plug which will promote a more complete combustion of the air-fuel mixture within the combustion cylinder resulting in a cleaner-burning less polluting engine operation.
It is yet another object of this invention to provide an air-injection spark plug which will be self-cleaning.
It is yet a further object of this invention to store a portion of the products of combustion, such products being hot gases, under pressure in an auxiliary pressure reducing chamber and subsequently release the hot gases back into the compression chamber of the cylinder, thus raising the temperature of the gases in the next compression cycle.
These and other objects of this invention are accomplished by providing an air-injection system in a spark plug comprising a decompression chamber with multiple inlets extending to the combustion cylinder.